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Comparison of Crepidula depressa and C. atrasolea. Typical C. depressa are white. The pinkish-brown streaks on the shell of this individual are not common. C. atrasolea has yellow coloration on the mantle and a sooty pigmentation on the foot. Some individuals are significantly darker than the animal in this photograph. Photo courtesy R. Collin, Smithsonian Tropical Research Institute.


Close-up of an individual C. depressa showing atypical body coloration. Photo courtesy R. Collin, Smithsonian Tropical Research Institute.

Species Name: Crepidula depressa Say, 1822
Common Name: Depressed Slippersnail
Synonymy: None
  1. TAXONOMY

    Kingdom Phylum/Division Class: Order: Family: Genus:
    Animalia Mollusca Gastropoda Caenogastropoda Calyptraeidae Crepidula

    Species Description

    The family Calpytraeidae is made up of three genera: Crepidula (slipper shells), Crucibulum (cup and saucer shells) and Calyptraea (hat shells). All of the species have limpet-shaped shells with an internal shelly septum. The genera are distinguished by shell morphology. In Crepidula the shell apex is directed posteriorly and the internal septum is a flat shelf that attaches along both sides of the shell. In Crucibulum the shell is conical with a central apex and a cup-shaped internal septum. In Calyptraea the shell is conical with a central apex but the internal shelly septum is a coiled ramp. Shells are often not diagnostic on the species level. Cryptic species often co-occur but they can usually be distinguished on the basis of developmental characters and body pigmentation. There are 6 species of Crepidula, one Crucibulum and one

    Calyptraea reported from Florida: Crepidula ustulatulina, C. depressa, C. atrasolea, C. aculeata, C. maculosa and C. fornicata, Crucibulum auriculum, and Calyptraea centralis.

    The shell of Crepidula depressa is generally flat and white, ranging from extremely recurved to somewhat convex depending on the habitat of the individual. Those from exposed substrates are often oval and convex. The septum is flat in convex shells and convex in recurved shells, with a notch on the right side where it attaches to the shell. There is also a depression in the center of the septal margin. Muscle scars are absent. The shell is white inside and out, rarely with pinkish-brown streaks. Length up to 4 cm. The translucent white body has opaque white on the tips on the tentacles and the lips and some white spots in the mantle and neck lappets. There is no black pigment on the foot and very little hint of yellow.

    Potentially Misidentified Species

    There are two easily confused congeners of Crepidula depressa living in the North Atlantic. Neither of these can be distinguished from C. depressa on the basis of adult shell morphology. Crepidula atrasolea co-occurs with C. depressa along the coast of Florida and can be distinguished from C. depressa by the black pigmentation on the foot and direct development. Crepidula plana has a white foot and planktonic larvae like C. depressa, but occurs from Nova Scotia south to Georgia, although its range may extend into Florida. These two species can be distinguished on the basis of details of the female reproductive tract and DNA sequence data (Collin 2000).

    Species with similar shells also occur in California, Chile, New Zealand, and the Mediterranean.

  2. HABITAT AND DISTRIBUTION

    Regional Occurrence

    Crepidula depressa occurs on the Gulf coast of Texas, the Yucatan Peninsula, and both the Gulf and Atlantic coasts of Florida at least as far north as Lake Worth.

    IRL Distribution

    Crepidula depressa has been documented to occur in the southern portion of the IRL. It is likely to have a more widespread distribution.

  3. LIFE HISTORY AND POPULATION BIOLOGY

    Age, Size, Lifespan

    Shell length in Crepidula depressa is typically to 4 cm.

    Locomotion

    Crawls. Hatchlings are planktonic for 3 - 4 weeks prior to settlement.

    Reproduction

    All calyptraeids are protandric hermaphrodites: small, young animals are males that later change to females as they grow. All species copulate. Females are able to store sperm for several months. The females deposit eggs into transparent capsules that they brood between the neck and the propodium. In some species, swimming larvae hatch from the capsules; in others, benthic juveniles crawl away from the capsules. Crepidula depressa embryos hatch into planktotrpohic larvae that persist for up to a month before settling.

    Embryology

    The small eggs produce typical planktotrophic veliger larvae with a smooth, almost planspiral shell at hatching. There are usually at least 100 eggs/capsule, but the number of eggs increases with female size. Average shell length at hatching is 255mm. The larvae take 3-4 weeks to grow to metamorphosis.

  4. PHYSICAL TOLERANCES

    Temperature

    Unknown

    Salinity

    Unknown

  5. COMMUNITY ECOLOGY

    Trophic Mode

    Species in all three genera of the Calyptraeidae are suspension feeders. They collect phytoplankton on mucus covering the gills. Phytoplankton are then transported to the mouth on a mucus string along the dorsal right side of the neck. The string is drawn into the mouth by the radula.

    Habitat

    Crepidula depressa are found in the low intertidal to subtidal zones where they typically utilize the shells of other mollusks for habitat.  They are most common living on shells and inside shells inhabited by hermit crabs. Maximum depth distribution is unknown.

  6. ADDITIONAL INFORMATION

    No information is available at this time

  7. REFERENCES

    Collin, R. 2002. Another last word on Crepidula convexa and a description of C. ustulatulina sp. nov. (Gastropoda: Calyptraeidae) from the Gulf of Mexico. Bulletin of Marine Science 70: 177-184.

    Collin, R. 2001. The effects of mode of development on phylogoegraphy and population structure of North Atlantic Crepidula (Gastropoda: Calyptraeidae). Molecular Ecology. 10: 2249-2262. [This includes, C. atrasolea, C. depressa and C. ustulatulina]

    Collin, R. 2000. Phylogeny of the Crepidula plana (Gastropoda: Calyptraeidea) cryptic species complex in North America. Canadian Journal of Zoology. 78: 1500-1514. [This includes C. depressa and C. atrasolea]

Report by: R. Collin, Smithsonian Tropical Research Institute
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Page last updated: Jan 2, 2005

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